1 members (ale348),
302
guests, and
14
robots. |
Key:
Admin,
Global Mod,
Mod
|
|
|
Joined: Oct 2000
Posts: 5,392
Member
|
Isn't that why we require boxes at every connection? I am a little curious how they created that bad a connection in a wirenut. That seemed to be the perfect storm of enough contact to create a circuit with enough resistance to burn up. I bet they had to try that quite a few times to get it right and a suspicious person would wonder if there was another substance involved. High R connections are the bane of older and/or DIY wiring Greg> This generally occurs before degrading to any form of 'arc',save for that which in mechanically introduced And is incendiary ,box or no box..... ~S~
|
|
|
|
Joined: Feb 2013
Posts: 264
Member
|
Sparky, I wasn't doubting that information. Just curious how often some of the forum members have encountered a screw on connector that was in the beginning stages of burning up.
A malfunction at the junction -------------------------------------- Dwayne
|
|
|
|
Joined: Oct 2000
Posts: 5,392
Member
|
Understood Potseal Fwiw, just what an arc is , how it's created ,and what the effects may be has been constitutes the heart of the issue. One of the UL papers CMP-2 points out in their '14 substantiations is Effectiveness of Circuit Breakers in Mitigating Parallel Arcing Faults in the Home Run Published literature from the early 1990s demonstrated the issue with high magnetic trip breakers failing to mitigate arcing faults: for example, as cited by Franklin.
Franklin’s work showed that 15A breakers manufactured in North America at the time exhibited widely varying magnetic trip levels, as low as 120A and potentially exceeding 800A. He contrasted this to European 15A breakers, which magnetically tripped at 100A, allowing far less arc energy to dissipate.
Franklin claims that experimental work with arcing faults shows that arcing currents are “almost always” in the range of 150A to 400A. He further states that an arcing current below 100A has “never” been observed. You'll find the av mag trips for afci's in the 75A range .... ~S~
Last edited by sparky; 05/29/16 01:48 PM.
|
|
|
|
Joined: Sep 2011
Posts: 66
OP
Member
|
And thats why I say arc faults are nothing more than re-branded short circuits. 75amps comes from the lowest anticipated short circuit in a dwelling. And ok, I get why it might make sense. But to this day it has NEVER been verified that a breaker tripping thermally rather than magnetically leads to fire.
|
|
|
|
Joined: Jul 2004
Posts: 9,923 Likes: 32
Member
|
That duplex looks more like it burned up from a bad connection at the plug cap than from a terminal fire.
Greg Fretwell
|
|
|
|
Joined: Jan 2005
Posts: 5,445 Likes: 2
Cat Servant Member
|
How did this devolve into an attack on AFCI's? IMO, that's another topic, one we have visited several times before.
It is the AFCI discussion that is responsible, in part, for my BS detector ringing at the very mention of "physics." This is because "physics" was raised in the AFCI debate, and I'm not at all happy with the discussions that followed.
Some made mention of "Paschen's Law" and assert that the law makes it impossible for an AFCI to operate at household voltages. Alas, apart from simple, brief entries that all trace back to the same source, I have not been able to find any general discussion of this purported 'law.' I would love to find this 'law' discussed in some standard physics or engineering text.
Conversely, I am troubled by the lack of rebuttal of this 'law' by industry, as well as the willingness of the code panel to continue to require something that can't exist.
As for testing at UL, I am greatly disturbed by the fact that UL does NOT test these devices for any sort of arc. A simple 'off' button in the device would allow it to pass the UL "test."
In addition, the AFCI industry has stridently opposed any manner of AFCI tester being developed. In effect, each AFCI maker is asking you to buy a product to protect you against a secret problem that only they can define.
As wonderful as the proposed 'glowing connection technology' may be, I remember the way the AFCI was brought into the code, with what can only be called 'bait and switch' tactics.
|
|
|
|
Joined: Oct 2000
Posts: 5,392
Member
|
How did this devolve into an attack on AFCI's? IMO, that's another topic, one we have visited several times before.
It is the AFCI discussion that is responsible, in part, for my BS detector ringing at the very mention of "physics." This is because "physics" was raised in the AFCI debate, and I'm not at all happy with the discussions that followed.
It's the other way 'round Reno The AFCI manufacturers have pursued and hounded Mr Charles for his GCI technology to levels of corporate espionage i dare not elaborate on in a pro forum. They know their product is flawed, and they do not wish to be revealed for it. They have shut down ever mode of communication ,save for venues like these, even shut down the original nema-afci task force guru when he came forward to do so. Some made mention of "Paschen's Law" and assert that the law makes it impossible for an AFCI to operate at household voltages. Alas, apart from simple, brief entries that all trace back to the same source, I have not been able to find any general discussion of this purported 'law.' I would love to find this 'law' discussed in some standard physics or engineering text. We've plenty available ..... It is difficult to find a general fault feature that performs well for all loads. Moreover, the residential electrical standard for single-phase alternating current (AC) is 120 V (60 Hz) in the United States, whereas it is 220–240 V (50–60 Hz) in other countries including China, Germany, Switzerland and Korea. Higher voltages more readily produce electrical fires caused by arc faults [49,50,51,52]. For example, the probability of fire ignition due to arc faults increases from 3.5% for 120 V to 83% for 240 V, and their nominal current levels are both 15 A [49]. Compared to 120 V, the higher voltages from 220 to 240 V are more likely to break down gaps and lead to more arcs [50,51]. Arc currents are usually continuous in higher voltage systems, but they are sometimes intermittent in 120 V systems [49,50]. Thus, higher voltage systems generate larger arc energy and thus provide better conditions for the ignition of electrical fires [50,51]. SourceConversely, I am troubled by the lack of rebuttal of this 'law' by industry, as well as the willingness of the code panel to continue to require something that can't exist. What you're witness to are personnel who have held multiple positions of one caliber or another re: CSPC,NEMA,UL & CMP-2 As for testing at UL, I am greatly disturbed by the fact that UL does NOT test these devices for any sort of arc. A simple 'off' button in the device would allow it to pass the UL "test." The original nema-afci task force admitted defeat , so nema simply hired new members. We can get into 1699 if you'd like ,plenty of manufacturer paid dissertations via high paid EE's willing to bend physics out there..... In addition, the AFCI industry has stridently opposed any manner of AFCI tester being developed. In effect, each AFCI maker is asking you to buy a product to protect you against a secret problem that only they can define.
As wonderful as the proposed 'glowing connection technology' may be, I remember the way the AFCI was brought into the code, with what can only be called 'bait and switch' tactics. True it's hard to pull one's self up by pulling another down in this industry Reno. But take it on faith ,they fired the first shot. And rightly so, if i ran a billion $$ industry, i'd bury anything confronting it quicker than a cat in a litter box Ergo, i'm siding with the underdog ,you (et all) are invited..... bad odds, lousy pay , long hours beating a keyboard to death, and possible early retirement ... ~S~
Last edited by sparky; 05/29/16 04:11 PM.
|
|
|
|
Joined: Jan 2005
Posts: 5,445 Likes: 2
Cat Servant Member
|
Well, there's the problem, in one quote:
"the probability of fire ignition due to arc faults increases"
Paschen's law, as explained, asserts that there simply cannot be an arc between copper electrodes, through air, at less than 327 volts.
Forget 'probability.' There is NO probability, ZERO chance, if something is physically impossible.
Either "Paschen's law" is in error, or AFCI's cannot work at household voltages (American or European). Period. Ever - because there cannot be an arc at household voltages. One might as well claim to detect unicorns.
I'm rather weary of convoluted 'conspiracy' theories, where some miracle product is being held back by an evil cabal, working behind the scenes, pulling strings. During the "oil crisis" of the 70's, there were all manner of claims regarding "400 mpg" carburetors and engines that ran on water. All, naturally, being held back by "big oil."
Frankly, even IF the AFCI industry were filled with evil trolls, a totally separate technology would be beyond their grasp. The French would rush to embrace it, if only to be 'different' from everyone else.
"Manufacturers' don't want ...." Ha! As if 'they' ever agreed on anything. It wasn't so long ago that our computers were bombarded by links claiming there was a simple way to make your own power, and that the 'energy companies didn't want you to know about it.' (Gee, I wonder where that guy went?)
I submit that, if the entire might of the civilized world cannot prevent third-world mud pits from developing nuclear weapons, then there is no way any 'manufacturers' could block new technology.
Lest readers forget, I have no use for AFCI's. That's been discussed many times in other threads. I'm not about to rush to embrace any other unproven ideas.
Remember the 'scientific theory?' Theory - hypothesis - experimentation - verification? It's amazing how many passionately held 'discoveries' fail to be repeatable by others.
Now ... as for detecting "glowing connections:" Assuming it was possible to detect a glowing, high resistance connection ... how could such a device distinguish between a loose terminal, and the operation of an ordinary toaster?
|
|
|
|
Joined: Oct 2000
Posts: 5,392
Member
|
Well, there's the problem, in one quote:
"the probability of fire ignition due to arc faults increases"
Paschen's law, as explained, asserts that there simply cannot be an arc between copper electrodes, through air, at less than 327 volts.
Forget 'probability.' There is NO probability, ZERO chance, if something is physically impossible.
Either "Paschen's law" is in error, or AFCI's cannot work at household voltages (American or European). Period. Ever - because there cannot be an arc at household voltages. One might as well claim to detect unicorns. Reno, the entire definition of 'arc' is literally being turned inside out by manufacturer paid studies but we can have arcs @ 120v, heck we can arc a doorbell circuit, the jist is it's sustainable incendiary effect I'm rather weary of convoluted 'conspiracy' theories, where some miracle product is being held back by an evil cabal, working behind the scenes, pulling strings. During the "oil crisis" of the 70's, there were all manner of claims regarding "400 mpg" carburetors and engines that ran on water. All, naturally, being held back by "big oil."
The only conspiracy would be big $$$ protecting it's turf. Frankly, even IF the AFCI industry were filled with evil trolls, a totally separate technology would be beyond their grasp. The French would rush to embrace it, if only to be 'different' from everyone else.
"Manufacturers' don't want ...." Ha! As if 'they' ever agreed on anything. It wasn't so long ago that our computers were bombarded by links claiming there was a simple way to make your own power, and that the 'energy companies didn't want you to know about it.' (Gee, I wonder where that guy went?)
I submit that, if the entire might of the civilized world cannot prevent third-world mud pits from developing nuclear weapons, then there is no way any 'manufacturers' could block new technology. Blocking and Owning technology are two distinctions that apply here. Thus the patent wars , and yes there have been multiple thermal copycats that have slipped thru it's loose litigant net.... Lest readers forget, I have no use for AFCI's. That's been discussed many times in other threads. I'm not about to rush to embrace any other unproven ideas.
Remember the 'scientific theory?' Theory - hypothesis - experimentation - verification? It's amazing how many passionately held 'discoveries' fail to be repeatable by others.
Now ... as for detecting "glowing connections:" Assuming it was possible to detect a glowing, high resistance connection ... how could such a device distinguish between a loose terminal, and the operation of an ordinary toaster?
simple point of use thermal dynamics an old concept re packaged stupid simple KISS stuff ~S~
Last edited by sparky; 05/30/16 10:56 AM.
|
|
|
Posts: 28
Joined: February 2011
|
|
|
|